In this project we will continue our studies of the immunological relationships between transplanted organs and their recipients in mice. We will be using both in vitro and in vivo tests of the specific cellular immune responsiveness and recipients, especially mice, bearing long-term, H-2 incompatible transplants of kidney or hearts with primary vascular union of the transplanted organs. In particular, we will be studying the new phenomenon, which we have discovered, of a specific transplant "killing effect" of long-term surviving organs brought about by immunopotentiating treatments including adjuvants and donor antigen. We will apply this approach to a variety of organ transplant systems and to certain transplanted tumors. We will also be studying the use of xenogeneic pancreatic islet cell transplants for the correction of streptocozin-induced diabetes in mice. Islets from rats have already shown considerable capacity to reverse the diabetic state in immunosuppressed, diabetic mice.